(1Field of the Invention
The present invention relates to a method for reclamating disturbed land areas without the excavation and use of earth materials. In particular, the present invention relates to a method for using relatively abundant non-hazardous residue waste materials to reclaim disturbed land areas. The waste materials preferably comprise a foundation of lime sludge combined with ash waste materials and/or concrete waste materials that need an environmentally acceptable method of disposal or utilization. As a solution, the waste materials are first rendered leach resistant by the method of the present invention. The leach resistant waste materials are then used as a fill material in land areas such as sand pits, gravel or stone pits, quarries, strip mine areas, mined areas, borrow pits, and other areas that have been disturbed by removal of earth materials. The reclamation process is thus unique in that it does not include the use of any earth materials such as soil, gravel, sand and the like that must be excavated to serve as fill material, thereby creating another pit or disturbed area. Finally, yard waste compost comprised of materials such as fugitive soil, leaves, grass clippings, tree trimmings and the like that have previously been composted are layered over the filled in waste materials. The yard waste compost provides for the establishment and support of vegetative growth as a cover over the reclaimed area. Therefore, the method of the present invention also eliminates the need to strip mine top soil to establish a suitable medium for vegetative growth.
(2) Prior Art
Lime sludge or residual lime sludge is waste material that is formed as a by-product when water is subjected to a softening process. The increased need for softened water in both public water systems and industrial water systems has resulted in an abundance of lime sludge. For decades, lime sludge material has been disposed of by placing a slurry of lime sludge containing between about 1% to 10% total solids into an impoundment reservoir. The lime sludge is then allowed to thicken and dewater through various methods including filtration/percolation, evaporation, or settling and supernatant removal through a decant structure. These methods increase the percent of total solids in the lime sludge to about 45% with the balance being water. The total solids accumulation rate of lime sludge held in the impoundment reservoir is therefore dependent on the rate of lime sludge generation and the size of the impoundment reservoir being filled. Once the impoundment reservoir holds a useable quantity of lime sludge, the lime sludge is removed from the impoundment reservoir and disposed of into an approved landfill (lined to contain the deposited materials) or applied on agricultural land as a soil conditioner.
However, what is needed is an alternative to these practices. The problem is that landfilling is increasing in cost as the availability of landfill space diminishes, making this method of disposal economically prohibitive. Also, the amount of lime sludge that can feasibly be used as a soil conditioner does not approach the large quantities that are in need of proper disposal. Furthermore, the increased supply over demand for lime sludge as a soil conditioner is making this method of disposal only marginally economical.
Another method useful for disposing of lime sludge is described in U.S. Pat. No. 4,852,269 to Glorioso, which combines a method for disposing of sewage sludge with a method for disposing of lime sludge. The lime sludge, which is produced as a by-product of water treating, is first reclaimed to product lime. The product lime can then be used as a softener in municipal water treatment. The process of reclaiming lime sludge is typically carried out at elevated temperatures and produces off gases that can be used to aid in drying and pelletizing the sewage sludge. The sewage sludge pellets can then be used as a soil conditioner. The problem is that more lime sludge is produced during the water treating process than is needed to be reclaimed to produce lime for later use as a water treatment additive. The net result is a build up of lime sludge that needs an acceptable method of disposal.
The prior art has also described various methods for stabilizing waste water or sewage sludge to form a hardened composition that can be used as a landfill. This method is described in U.S. Pat. No. 4,028,130 to Webster et al where sewage sludge is combined with certain types of cementitious reactants, such as hydrated lime and fly ash, to form hardenable compositions. These compositions can also include alkaline earth metal sulfates and/or soil or other inert or complimentary additives. These hardenable compositions may be placed in a suitable site, open to the atmosphere where landfill or road base is needed and then permitted to harden over a period of time.
Other methods for disposing of waste water sludge or sewage sludge generally comprise the steps of preliminarily dewatering the sludge to increase its dry solids content and then adding a cementitious reactant such as calcium (quicklime) and/or fly ash to further dry and sterilize the sewage sludge. The resulting product can then be formed into granules or pellets that are useful as an agricultural fertilizer. The pellets can be scattered by a conventional fertilizer spreader. Illustrative of this prior art is U.S. Pat. Nos. 3,476,683 to Liljegren; 4,270,279 to Roedioer; 4,306,978 to Wurtz; 4,554,002 to Nicholson; 4,761,893 to Glorioso and 4,997,572 to Wurtz.
What is needed is an alternate method or process for disposing of lime sludge that does not require that the lime sludge be deposited in an approved landfill or used in an agricultural application as a soil conditioner. Landfills are rapidly decreasing in availability resulting in a dramatic increase in the cost of landfilling disposable materials. Also, unstable waste water sewage sludge can create serious environmental concerns relative to leaching and ground water contamination. Furthermore, disposing of lime sludge in a fertilizer application is an increasingly used practice that has reached the point of demand saturation. Thus, the cost benefit of this disposal method has decreased to the point of being marginal.
Similar to lime sludge, ash materials, which are the residue of coal and wood combustion (bottom ashes and/or precipitated fly ashes) are very plentiful and their disposal or utilization is a primary concern to generators of these materials and those officials responsible for overseeing and enforcing landfill regulations. The major concerns with respect to ash materials include fugitive dust loss of the ashes into the air, leaching of pollutants contained in the ashes to ground water and surface run off of ash particulate into surface waters. As with lime sludge, disposal of ash materials in landfills is an economically expensive solution. In addition, ash materials contain appreciable amounts of heavy metals that can leach into the ground water if the ash materials are not first rendered leach resistant. This is a major concern for landfill operators and prohibits their use as an agricultural soil conditioner. Therefore, what is also needed is an economically and environmentally acceptable means of disposing of residue ash materials.
For the same reasons, the disposal of concrete waste materials in landfills is economically prohibitive. In addition, the finely powered composition of dry concrete material makes it difficult to use in a fertilizer application.